Process of manufacture of unfermentable fruit juices



' Patented Feb. 13, 1934 its) STATES PATENT OFFICE PROCESS OFMANUFACTURE OF UNFER- MENTABLE FRUIT JUICES Silvere Cyril Vandecaveye,Pullman, Wash., assignor .to State College of Washington, Pullman, Wash.

2 Claims.

w tion of chemical preservatives but no satisfactory method has hithertobeen devised for the removal from the fruit juices of the mineral foodsupplies essential for the growth and reproduction of fruit juices.

Instead of depending solely upon the agencies of pasteurization,sterilization by heat, refrigeration, or the addition of chemicalpreservatives, I employ, to assist in rendering fruit juicesunfermentable, successive inoculations of the fruit juices with yeastsor yeast suspensions to remove from the fruit juices practically all thenitrogen and phosphorus, both of which are essential ele- -ments for thegrowth and reproduction of the 5 yeasts that cause the production ofethyl alcohol in the fruit juices by the process of fermentation.

The characteristic feature of the process resides in allowing to growand multiply until ethyl alcohol is just beginning to be formed, theyeasts naturally present in the fruit juices, or those derived fromcultures isolated from fruits or any other substances containing yeastscapable of producing ethyl alcohol, and introduced into the fruit juicesby inoculation. Cultures thus isolated are hereinafter designated asyeast culture. The yeasts developed in this manner in the fruit juicesand hereinafter designated as generation of yeasts, are then preventedfrom further development by heating the fruit juices so treated at 40 C.or above for 20 minutes or more. The heating also causes theprecipitation of the yeast cells which have already consumed a largepart of the nitrogen and phosphorus contained in the fruit juices undertreatment. The precipitate thus formed is then separated and removed bydecantation or siphoning of the supernatant fruit juice.

Further removal of the nitrogen and phosphorus remaining in the decantedor siphoned fruit juice is secured by subsequent inoculations with fruitjuices naturally containing yeasts capable of producing ethyl alcohol,or with suspensions of yeast culture, allowing the yeasts thusintroduced to grow and multiply until ethyl alcohol is just beginning tobe formed. These yeasts, which may be conveniently referred to as thesecof the yeasts that cause alcoholic fermentation 0nd generation ofyeasts, are then prevented from further development by heatinprecipitating,

and decanting or siphoning, according to the specifications describedfor the first generation of yeasts. Inoculation, heating, precipitation,and

decantation or siphoning is repeated according to the specifications forthe preceding generations of yeast until only traces of nitrogen andphosphorus remain in the fruit juices. Usually three inoculations,beatings, precipitations, and decantations or siphonings are suflicientto remove from the fruit juices all but traces of nitrogen andphosphorus.

When all but traces of the nitrogen and phosphorus are thus removed fromthe fruit juices the production of-ethyl alcohol by yeasts is virtuallyimpossible for the simple reason that the two elements, nitrogen andphosphorus, are required in perceptible quantities for the growth,reproduction, and activity of yeasts. Consequently, by the use of thisprocess the fruit juices are said to be immunized or vaccinated againstyeasts that cause the production of ethyl alcohol, and the total amountof ethyl alcohol produced in fruit juices may be controlled to as lowand lower than 0.5 of one per cent.

It may be remarked that the underlying principle of this processconsists in the removal of all but traces of the nitrogen and phosphoruscontained in fruit juices by means of inoculation, growth, and removalof successive generations of yeasts. Obviously the traces of nitrogenand phosphorus together with the living yeast cells remaining in thefruit juices after this process or principle has been carried tocompletion may be responsible for the production of limited, smallamounts of ethyl alcohol in the fruit juices following storage for acertain period of time. This possible production of ethyl alcohol may beprevented completely by passing the processed fruit juices through anyfilter that will retain all the yeast cells or by adding to theprocessed fruit juices 0.4 of one per cent sodium benzoate previoustofinally placing the unfermentable fruit juice into containers forstorage of the product.

The following is an example of a convenient mode of procedure for theproduction of uniermentable fruit juices by the described process usingthe principle of inoculation with, and growth and removal of, successivegenerations of yeasts:

1. Inoculate freshly pressed fruit juice with two per cent of aconvenient suspension of yeast culture.

2. Keep or incubate the inoculated fruit juice at C. and allow the yeastto develop until foam bubbles indicate carbon dioxide production, andconsequently the beginning of ethyl alcohol formation. r

3. Check further development of the yeasts by heating the fruit juice at45 C. for to minutes, cool to 25 0., allow the precipitates to settle,and siphon the supernatant fruit jnice.

4. Take the siphoned supernatant fruit juice and repeat the inoculation,incubation, heating,

and siphoning as described above a second and a third time.

5. Following the third inoculation, incubation,-heating, and siphoningof the fruit juice, add sodium benzoate at the rate of 0.4-. of one percent, mix thoroughly, and place the processed juice in suitablecontainers, or, instead 01 adding sodium benzoate, pass the processedfruit juice through any filter that will retain all the yeast cells andcollect the filtrate immediately in containers previously sterilizedagainst yeasts, filling these containers to the top to exclude the airfrom the fruit juice.-

6. Immediately after filling containers with the filtered or the sodiumbenzoate treated fruit juice, close them with stoppers or capspreviously sterilized against microorganisms to prevent possiblebacterial and mold growth that may result from unsterilized stoppers orcaps. This application is a substitute for application Serial No.447,782, filed April 26, 1930.

I claim:

1. The process which comprises treating saps and juices from ediblefruits by means of generations of yeasts derived from the yeastnaturally present in such fruits as follows: (1) keeping the saps andjuices from edible fruits at any temperature favorable for yeastdevelopment, allowing such development to proceed until foam bubblesindicate carbon'dioxide production and consequently the beginning ofethyl alcohol formation; (2) checking further development of the yeastsand precipitating them by heating the above mentioned saps' and fruitjuices at and above C. for 30 to 40 minutes and then cooling them to 25C. for the purpose of promoting w a new generation of yeast by means ofinoculation with fresh saps and fruit juices from edible fruits; (3)allowing the precipitates of the above treated saps and fruit juices tosettle, and separating the clearer from the settled portion of 35 thesesaps and fruit juices; (4) repeating inoculatlon, precipitation, andseparation of the clearer from the precipitated portion of the saps andfruit juices as above described for the purpose of removingsubstantially all nitrogen and phosphorus therefrom.

2. Treating saps and juices from edible fruits with yeasts derived fromcultures as follows: (1) inoculating the above mentioned saps and fruitjuices with yeast culture and keeping such inoculated saps and fruitjuices at any temperature favorable for yeast development, allowing suchdevelopment to proceed until foam bubbles indicate carbon dioxideproduction and consequently the beginning of ethyl alcohol formation;(2) checking further development of these yeasts and precipitating themby heating the above mentioned saps and fruit juices at and above 45 C,for 30 to 40 minutes and then cooling them to 25 C-. for the purpose ofpromoting a new generation of yeast by means of inoculation with yeastculture; (3) allowing the precipitates of the above treated saps andfruit juices to settle, and separating the clearer from the settledportion of these saps and fruit juices; (4) repeating inoculation,precipitation, and separation of the clearer from the precipitatedportion of the saps and fruit juices'as above described for the purposeof removing substantially all nitrogen

